Assuring dropout of solenoid valve controlled by peak-and-hold driver

Abstract

Systems and methods of controlling a solenoid coil in a solenoid valve provide a controller that allows a supervisory or leakage current to be used in a peak-and-hold driver. The controller introduces a delay time after detection of a dropout voltage that prevents the solenoid coil from being immediately re-energized in order to ensure proper dropout of the solenoid coil. The delay time imposes a wait period during which the controller takes no action with respect to the current in the solenoid coil, allowing the solenoid coil to deenergize and return the valve to its normally-open or normally-closed position. Such use of a delay time may be limited to instances where the controller has already gone through a power-up cycle such that the response time needed by the controller to energize the solenoid coil is minimized, thus reducing the valve startup time.